Recent controversy in hominid ancestry

Over the past decade, a series of controversies have engulfed evolutionary theory, as an array of fossil discoveries have provided new knowledge on the fossil record. However, these discoveries have been so controversial as to require even major publications begin acknowledging, first in 2001 after the discovery of O. tugenesis, and climaxing in 2007 with the discovery that Habilis and Erectus coexisted, that the human evolutionary tree now looks like a "bush with many branches". One after another of the species previously labeled "missing links," ancestors of modern humans, have been conceded to be "offshoots" because of early complexity, as they are discovered to walk upright, coexist with other hominins, or prove similar to modern humans, rather than showing early similarity to apes.[1]

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"The new research by famed paleontologist Meave Leakey in Kenya shows our family tree is more like a wayward bush with stubby branches, calling into question the evolution of our ancestors. The old theory was that the first and oldest species in our family tree, Homo habilis, evolved into Homo erectus, which then became us, Homo sapiens. But those two earlier species lived side-by-side about 1.5 million years ago in parts of Kenya for at least half a million years, Leakey and colleagues report in a paper published in Thursday’s issue of the journal Nature... Overall what it paints for human evolution is a 'chaotic kind of looking evolutionary tree rather than this heroic march that you see with the cartoons of an early ancestor evolving into some intermediate and eventually unto us,' Spoor said in a phone interview from a field office of the Koobi Fora Research Project in northern Kenya."

Essentially we've found a number of new hominins and these have been wreaking havoc on evolutionary theory over the past decade. Sahelanthropus tchadensis, Orrorin tugenensis, and Ardipithecus ramidus (Ardi) now make for our three oldest hominin fossils. Trouble is, they are way too human-like, showing far more early complexity and similarity to modern humans, including evidence of early bipedalism, than was supposed to exist so far back in the human lineage.[3] The discovery of such early bipedalism was then followed by discoveries that A. afarensis (Lucy)[4] and A. sediba also walked upright.[5]

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"Another discovery by Dr. Leakey challenged the prevailing view that the family tree had a more or less single trunk rising from ape roots to a pinnacle occupied by Homo sapiens. Yet here was evidence that the new species Kenyanthropus platyops co-existed with Lucy’s afarensis kin. The family tree now looks more like a bush with many branches. 'Just because there’s only one human species around now doesn’t mean it was always that way,' Dr. Grine said... Two even earlier specimens are even harder to interpret. One found in Kenya by a French team has been dated to six million years and named Orrorin tugenensis. The teeth and bone pieces are few, though the discoverers think a thigh fragment suggests that the individual was a biped — a walker on two legs. Another French group then uncovered 6.7-million-year-old fossils in Chad. Named Sahelanthropus tchadensis, the sole specimen includes only a few teeth, a jawbone and a crushed cranium... Other challenges arise from human evolution in more recent epochs. Just who were the 'little people' found a few years ago in a cave on the island of Flores in Indonesia? The Australian and Indonesian discoverers concluded that one partial skeleton and other bones belonged to a now-extinct separate human species, Homo floresiensis, which lived as recently as 18,000 years ago."

We've also discovered species which were supposed to be linear descendants of one another actually coexisted, and thus couldn't have evolved from one another. Homo erectus and Homo habilis both coexisted, Australopithecus afarensis (Lucy) and Australopithecus ramidus (Ardi) both coexisted, and we even found some brand new fossils that coexisted with modern humans and Neanderthals, like Homo floresiensis ('Hobbit Man') and the Denisovans. According to Encyclopaedia Britannica's current dating of Australopiths, Ar. kaddaba and Ar. ramidus coexisted; A. afarensis, K. platyops, A. bahrelgazali, and A. africanus all coexisted; P. aethiopicus, A. africanus, A. garhi, H. habilis, and H. rudolfensis all coexisted; and A. sediba, P. boisei, H. rudolfensis, and H. habilis all coexisted as well.[7] A large number of hominins therefore coexisted and thus are 'offshoots' which could not have evolved from one another, resulting in a messy 'bush'.

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"A new discovery suggests that Homo erectus may not have evolved from Homo habilis—and that the two may have been contemporaries. The phrase 'family bush' doesn't trip off the tongue the way 'family tree' does, but anyone talking about human evolution had better get used to it. For years, scientists who study human origins have known that the simple model in which one human ancestor evolved into another in a nice, linear fashion is a myth. Instead, starting 4 million years ago, half a dozen species in the genus Australopithecus lived in Africa at the same time. Only one is our direct ancestor; the others were evolutionary dead ends, failed experiments. But experts thought that once the Homo lineage debuted about 2.5 million years ago in East Africa with Homo habilis, things settled down, with habilis evolving into Homo erectus who evolved into Homo sapiens—us—like biblical begats. Two fossils discovered in Kenya suggest that evolution was a lot messier than that."

2000: Orrorin tugenensis

The discovery of O. tugenensis proved problematic for evolutionary theory because, despite being much older than "Lucy," it walked upright and was "in a more advanced stage of evolution". It also called into question the Savannah Hypothesis and conventional evolutionary theory

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"French and Kenyan scientists have unearthed what they believe to be the oldest remains of a hominid, or ape-man, ever found. Although the fossils themselves have not been dated, the rock in which they were discovered is known to be six million years old... 'Not only is this find older than any other previously known, it is also in a more advanced stage of evolution,' KPE palaeontologist Dr Martin Pickford told a news conference in Nairobi."

"This indicates a divergence between Hominidae and Gorillidae that dates back to a substantial period prior to 6 Ma, and we estimate about 8-7 Ma for this event. If so, then the discovery of Orrorin refutes all hypotheses in which humans diverged from apes later than 7 Ma, including most of the recent estimates by molecular biologists who tend to think of the divergence as having taken place later than 5 Ma, and even as recently as 2.5 Ma. In other words, the much vaunted 'molecular clock' seems to be telling us the wrong time. The fact that Orrorin is found with other fauna that indicates a wooded to forested environment, tends to refute the 'savannah' hypothesis of human origins. It seems more likely now that bipedalism originated from an arboreal ancestor, rather than via a knuckle-walking ground dweller similar to chimpanzees. Thus, previous palaeoecological and palaeoenvironmental scenarios of human origins will need to be reconsidered in light of the new data."

2001: Afarensis and Ramidus coexisted

It turns out Lucy (A. afarensis) wasn't alone, but lived at the same time as another australopithecine. The discovery that two hominins that were supposed to be descended from one another, one of them the famous "Lucy", lived at the same time, led for the first time to the phrase "bush" being used instead of tree.

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"Now it seems that the fossil species Australopithecus afarensis, which lived from about four million to three million years ago and is best known from the celebrated Lucy skeleton, was not alone on the African plain. Lucy may not even be a direct human ancestor after all. Indeed, the family tree, once drawn with a trunk straight and true, is beginning to look more like a bush, with a tangle of branches of uncertain relationship leading in many directions."

2002: Sahelanthropus tchadensis more proof of early bipedalism

Once again, the term "bush" is used to describe the implications of an early ancestor. With Orrorin tugenesis, S. tchadensis remains by far our oldest discovered fossils, and like O. tugenesis, it shows evidence of early bipedality, rather than similarity to apes.

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"When I went to medical school in 1963, human evolution looked like a ladder," he [anthropologist Bernard Wood] says. The ladder stepped from monkey to man through a progression of intermediates, each slightly less ape-like than the last. Now human evolution looks like a bush. We have a menagerie of fossil hominids - the group containing everything thought more closely related to humans than chimps. How they are related to each other and which, if any of them, are human forebears is still debated... Based on this, we might have to question some species' place in the hominid club. If Australopithecus looks more ape-like than a much older fossil, how can it belong to the human family? 'Anything with a more primitive face has to have its membership reviewed,' says Wood. No groups will be expelled on the evidence so far. The real lesson, says Wood, is that appearances are a bad guide to evolutionary relations. Hominid and ape species probably mixed and matched from a set of features, he says, with the same traits evolving independently on multiple lineages."

"The reconstruction shows that the opening in the base of the skull through which the spinal cord passes, called the foramen magnum, is oriented so that the neck points downwards. But in apes, such as gorillas, the neck point backwards, explains Dan Lieberman, a palaeoanthropologist at Harvard University in Cambridge, Massachusetts and a member of Brunet's team. The virtual reconstruction shows that Toumaï probably walked upright with head held aloft. This means that Toumaï's head balanced on top of its spine, suggesting an upright walking stance. 'The evidence certainly suggests that Toumaï was a biped,' says Lieberman... Lieberman, on the other hand, points out that all of the earliest known bipeds, such as the hominid Australopithecus afarensis, which is about half as old as Toumaï, had large neck muscles. 'This work confirms that Toumaï is the earliest and most complete hominid, and suggests that the earliest hominids were bipedal,' claims Lieberman. 'And that's big news.'"

"What is remarkable about the chimp-sized cranium TM 266-01-060-1 discovered by Brunet et al. is its mosaic nature. Put simply, from the back it looks like a chimpanzee, whereas from the front it could pass for a 1.75-million-year-old advanced australopith. The hominid features involve the structure of the face, and the small, apically worn, canine crowns. Other hominid features are found in the base of the cranium and in the separate jaw fragment. If we accept these as sufficient evidence to classify S. tchadensis as a hominid at the base, or stem, of the modern human clade, then it plays havoc with the tidy model of human origins. Quite simply, a hominid of this age should only just be beginning to show signs of being a hominid. It certainly should not have the face of a hominid less than one-third of its geological age. Also, if it is accepted as a stem hominid, under the tidy model the principle of parsimony dictates that all creatures with more primitive faces (and that is a very long list) would, perforce, have to be excluded from the ancestry of modern humans."

2003: Neanderthal an offshoot

The finding of three skulls reveals humans and Neanderthals lived side by side, and thus could not be evolved from each other.

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"Prior to the discovery of these fossils, evidence for the out-of-Africa theory of evolution for modern humans was largely based on the analysis of genetic variation in people alive today. Archaeological evidence from 100,000 to 300,000 years ago was scarce. As a result, another theory that modern humans evolved simultaneously in various parts of the world at roughly the same time from ancient local populations, such as the Neanderthals in Europe, maintained plausible traction. Timothy White, a paleoanthropologist at the University of California at Berkeley, said that the fossils he and his colleagues found in Ethiopia fill this gap in the archaeological record and support the argument that Neandertal was an evolutionary side branch unrelated to modern humans... 'This would signal the importance of culture in these ancient hominids, which should not come as a surprise to us," she said. 'I expect they were much more like us than we have given them credit for being.'"

2004: Hobbit Man lived recently

The discovery of a diminutive species living on the island of Flores until the past 18,000 years proves difficult for evolutionary theory, because there's no explainable lineage for the new species. As a result, attempts are made to explain the fossil as a modern human suffering from microcephaly, a degenerative disease.[16]

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"When the remains of a tiny species of human were discovered on the remote Indonesian island of Flores (as reported in Nature last month1,2), it was clear that the story was going to have far-reaching implications. The one-metre-tall hominids jolted palaeoanthropologists' notions of what it means to be human, and challenged the idea that Homo sapiens has long been the only human species on this planet."

"Homo floresiensis, dubbed the 'hobbit' of Indonesia, is once again igniting debate. A skull-scanning study supports the idea that the diminutive individual was not a separate species, but simply a stunted human... The 18,000-year-old fossil stunned the anthropology community when it was discovered in a limestone cave on the Indonesian island of Flores in 2003. The young adult female lived relatively recently, yet was unlike any other hominid species known — she was only a metre tall, with long limbs relative to her torso and a tiny cranium compared with the modern humans living elsewhere on the planet at the time. She was reported in Nature as a new and completely unexpected species of human: H. floresiensis. Researchers have since clashed over whether the skull really does represent a different species or merely a deformed Homo sapiens — perhaps the result of dwarfism or microcephaly, a developmental disorder that results in a very small skull and brain... But palaeoanthropologist William Jungers of Stony Brook University in New York isn't convinced by Holloway's conclusions either. 'They note a fascinating similarity in the cranial measurements found in Homo floresiensis and Australopithecus but ignored it in favour of making the microcephaly argument,' he says. 'A weird decision, but hobbit politics as usual.'"

2005: First chimp fossil found - ever

For the first time, a chimp fossil was found - which only serves to highlight how frustrating it's been for paleontologists until now that they couldn't find any. After all, it's kind of hard to say we evolved from chimps if chimps don't appear to have existed long ago. It also weakened the Savannah Hypothesis (theory for human bipedality) trying to explain that humans and chimps separated in evolution because chimps stayed in the jungles of western and central Africa, since the new fossils were found east of the Rift Valley.

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"Palaeontologists digging in the dusty wastelands of East Africa have discovered the first known chimpanzee fossil. The modest haul of just three teeth is the first hard evidence of the evolutionary path that led to today's chimpanzees. As well as shedding light on chimps, the find throws up new questions about human evolution; it seems that chimpanzees may not have been physically separated from humans as was once thought. That no one had previously found a chimpanzee fossil had long been a frustrating puzzle, comments Sally McBrearty, an anthropologist at the University of Connecticut, who made the find near Lake Baringo, Kenya, with her colleague Nina Jablonski. Set against the many human fossils found in East Africa, the lack of specimens documenting the chimp's evolutionary story was exasperating... Previous theories suggested that chimps never crossed east of the Rift Valley, but instead stayed in the jungles of western and central Africa. Some even suspected that this physical separation was what set the earliest chimp and human ancestors on contrasting evolutionary voyages. But now McBrearty has stumbled on chimp remains east of this divide. This means we need a better explanation of why and how chimps and humans went their separate evolutionary ways, McBrearty says. The discovery that chimps were living in semi-arid conditions as well as in the jungle seems to blow apart the simplistic idea that it was the shift to savannah that led to humans walking upright."

2007: O. tugenesis and Sahelanthropus offshoots

After finding they lived at the wrong time, with other supposed missing links, the two are declared offshoots.

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"The lineages of humans and chimpanzees, our closest relatives, diverged from one another about 4.1 million years ago, according to a new estimate that is said to be far more precise than previous ranges for this critical evolutionary moment. However, the claim is a bad match with previous estimates based on fossil evidence and other genetic work... The new estimate supports claims that recently discovered primate fossils, the Millennium man (Orrorin tugenesis) and Sahelanthropus, are not on the human lineage but belong rather to an ancestral lineage from which both humans and chimps evolved... 'Chimps are knuckle-walkers and hominids are bipeds,' he said, 'and it's inconceivable that you could have a common ancestor to both at 4 million years ago when you already have evidence in the hominid lineage that there were bipeds already around at that time.'"

2007: Habilis and Erectus coexisted

Meave Leakey, part of the famous Leakey family, in 2007 made the startling discovery that two of the most major evidences for the human evolutionary tree lived side by side, making it unlikely one descended from the other as commonly believed. This discovery leads to multiple major news publications acknowledging the human evolutionary tree now looks like a messy bush. The 3 articles shown at the top of this section, by John Noble Wilford, Seth Borenstein, and Sharon L. Begley were all written in response to this extremely controversial discovery.

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"The new fossil evidence reveals an overlap of about 500,000 years during which Homo habilis and Homo erectus must have co-existed in the Turkana basin area, the region of East Africa where the fossils were unearthed. 'Their co-existence makes it unlikely that Homo erectus evolved from Homo habilis,' said co-author Professor Meave Leakey, palaeontologist and co-director of the Koobi Fora Research Project."

"Two fossils unearthed in Kenya have added a new dimension to our view of life at the birth of our Homo genus. They show that two ancestral human species seem to have lived cheek-by-jowl in the same area, much as gorillas and chimpanzees do today... The fact that these two species seem to have been contemporaries is a surprise to anthropologists, say Fred Spoor of University College London and his colleagues, who discovered the hominin fossils seven years ago and now describe them in this week's Nature. Anthropologists have tended to see the evolution of Homo species as a linear progression, beginning with H. habilis and passing through H. erectus before ending up with modern humans. But it seems the path through time was broad enough for more than one species to walk abreast, with H. erectus and H. habilis living in the same place at the same time for as much as half a million years. Spoor and his colleagues argue that this makes it less likely that H. erectus was a direct descendant of H. habilis, instead suggesting that there is a common ancestor yet to find."

2009: Erectus footprints show modern foot

Newly discovered footprints cast even further doubt on the belief we once looked like apes, and more evidence for bipedalism in ancient humans.

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"Footprints uncovered in Kenya show that as early as 1.5 million years ago an ancestral species, almost certainly Homo erectus, had already evolved the feet and walking gait of modern humans... Studying the more than a dozen prints, scientists determined that the individuals had heels, insteps and toes almost identical to those in humans, and that they walked with a long stride similar to human locomotion."

2009: Russell Ciochan admits his fossil was ape not hominin

In an unusual recantation, Russell L. Ciochan, who discovered the Longuppo fossil, admits he now believes he and other paleontologists were wrong in calling the fossil of the human lineage, and that he now believes, given the discovery of Homo floresiensis, that his fossil is of an extinct ape.[24] He does so to try and explain where the mysterious "Hobbit Man" could have come from, since there otherwise remains no explanation for its unusual appearance in the fossil record.

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"For many years, I used Longgupo to promote this pre-erectus origin for H. erectus finds in Asia. But now, in light of new evidence from across southeast Asia and after a decade of my own field research in Java, I have changed my mind. Not everyone may agree; such classifications are always open to interpretation. But I am now convinced that the Longgupo fossil and others like it do not represent a pre-erectus human, but rather one or more mystery apes indigenous to southeast Asia's Pleistocene primal forest... The problem is that no comparable wrist or foot bones are known for H. erectus, making it impossible at this time to exclude a local variant of H. erectus as the ancestor of the Liang Bua 'hobbit'. So our claim of a pre-erectus African hominin living in east Asia fell into a long line of such arguments... But more than a decade after the discovery, with some distance from the subject, the teeth in Wang's lab looked distinctly more ape-like than hominin."

2009: 'Ardi' shows humans weren't like chimps

The new discovery of Ardipithecus Ramidus, nicknamed "Ardi", dispels the popular notion that humans once looked like modern chimps, and indeed that we were anything like them.[26] Also, Ardi proves to have very strong evidence of being a biped; an upright walker. One paleontologist, Alan Walker, remarks that "This find is far more important than Lucy", given that it was older than Afarensis, the famous "Lucy". National Geographic's Jamie Shreeve in October 2009 announced that, "If White and his team are right that Ardi walked upright as well as climbed trees, the environmental evidence would seem to strike the death knell for the 'savanna hypothesis'—a long-standing notion that our ancestors first stood up in response to their move onto an open grassland environment."[27] Shortly after this was publicized again in March 2010 by Smithsonian Magazine,[28] the claim that Ardi lived in the woodlands was attacked by Evolutionists because of its threat to the Savannah Hypothesis.[29]

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"Move over Lucy. And kiss the missing link goodbye... The fossil puts to rest the notion, popular since Darwin's time, that a chimpanzee-like missing link—resembling something between humans and today's apes—would eventually be found at the root of the human family tree. Indeed, the new evidence suggests that the study of chimpanzee anatomy and behavior—long used to infer the nature of the earliest human ancestors—is largely irrelevant to understanding our beginnings... 'This find is far more important than Lucy,' said Alan Walker, a paleontologist from Pennsylvania State University who was not part of the research. 'It shows that the last common ancestor with chimps didn't look like a chimp, or a human, or some funny thing in between... 'All of a sudden you've got fingers and toes and arms and legs and heads and teeth,' said Tim White of the University of California, Berkeley, who co-directed the work with Berhane Asfaw, a paleoanthropologist and former director of the National Museum of Ethiopia, and Giday WoldeGabriel, a geologist at Los Alamos National Laboratory in New Mexico. 'That allows you to do something you can't do with isolated specimens,' White said. 'It allows you to do biology.'"

"The discovery of Ar. ramidus also requires rejection of theories that presume a chimpanzee- or gorilla-like ancestor to explain habitual upright walking. Ar. ramidus was fully capable of bipedality and had evolved a substantially modified pelvis and foot with which to walk upright. At the same time, it preserved the ability to maneuver in trees, because it maintained a grasping big toe and a powerful hip and thigh musculature."

"Detailed descriptions of the skeleton, of a fairly complete 4.4-million-year-old female, show that humans did not evolve from ancient knuckle-walking chimpanzees, as has long been believed. The new fossils of Ardipithecus ramidus — known as 'Ardi' — offer the first substantial view of the biology of a species close to the time of the last common ancestor shared by humans and apes. Like modern humans, Ardi could walk upright and didn't use her arms for walking, as chimps do. Still, she retains a primitive big toe that could grasp a tree like an ape... Ardi's hands and wrists don't show several distinctive chimp characteristics, such as some larger bones and a tendon 'shock absorber' system to withstand bodyweight, says team member Owen Lovejoy of Kent State University in Ohio. The foot, with its big toe sticking out sideways, would have allowed Ardi to clamber in trees, walking along branches on her palms. And her teeth show no tusk-like upper canines, which most apes have for weapons or display during conflict. 'This is a major feature showing that Ardi is not in the lineage of modern chimps,' Suwa says."

2010: Denisovans coexisted with modern humans, Neanderthals

Turns out another surprise fossil was around at the same time as humans and Neanderthals, so to explain their dating methodologies of it, evolutionists now have to explain where this latest offshoot came from lineage-wise.[32][33]

2011: 'Lucy' walked upright

It's officially announced Lucy, the most famously heralded missing link, was a biped and walked upright, rather than being a tree-climber as previously believed. The discovery probably is influenced by the find of Ardi over a year earlier.

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"An unprecedented fossil foot bone appears to confirm that Australopithecus afarensis—the early human ancestors made famous by the "Lucy" skeleton—walked like modern humans, a new study says... Revealed in 2009, Ardi helped dispel the notion that a chimplike missing link occupied the base of the human family tree. Ardi's 'foot was already a pretty good bipedal foot, although that species retained an opposable great toe.' A. afarensis's foot now appears far more advanced than previously thought, Lovejoy said."

"Turns out, Lucy wasn’t in the sky at all; she was grounded just like us. The 3.2 million-year-old skeleton considered a predecessor to modern man had arches in her feet, meaning she didn’t climb trees as previously thought, researchers have found... 'We had this idea that Australopithecus afarensis was part ape and part human and partly still tree-climbing,' said Carol Ward, an MU researcher in the Department of Pathology and Anatomical Sciences at MU’s School of Medicine. Instead, they 'were walking just like we do.'"

2011: A. sediba too complex, considered offshoot

Five papers were published in the journal Science revealing how unclear it is to researchers how the fossil can relate to other relatives, given its extreme uniqueness.

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"But Wood says the species' unique mix of primitive and modern anatomy, particularly its foot, underscores the difficulty in determining whether any fossil represents a direct human ancestor or an evolutionary dead-end with some human traits. 'I think we had this crazy notion that our morphology and our behaviour were so special that they couldn't have conceivably evolved more than once,' he says, adding that the papers 'will make identifying human ancestors a hell of a lot more difficult today than it was yesterday.'"

Earlier in 2010, researchers tried to label it as a member of the human lineage, only to be accused of bias by their fellow researchers. Most controversially, the Director of the Institute for Human Evolution at the University of Witwatersrand, Francis Thackeray, concluded at the end of the paper that "The new fossil has a suite of characters which confirm that there is no clear boundary between Australopithecus africanus and Homo", which if true, means Africanus might as well just be called a modern human rather than a primitive ancestor.[36] These discoveries have led to the acknowledgement by Leslie C. Aiello, President of the Wenner-Gren Foundation for Anthropological Research, that a number of prior hypotheses must be rejected on the basis of such new discoveries.

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"Most of the recent effort in hominin palaeontology has been focused on Africa and Europe. But the announcement in 2004 of the small hominin Homo floresiensis in Indonesia was a warning that we are naive to assume we know more than the basic outline of human evolutionary history. If H. floresiensis is indeed a surviving remnant of early Homo that left Africa around 2 million years ago, we have to reject the long-standing idea that Homo erectus was the first African emigrant. We also must reject many hypotheses concerning the prerequisites for this emigration, such as a relatively large brain size, large body size and human-like limb proportions. Importantly, we must confront our relative ignorance about human evolution outside Europe and Africa."[37]

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2011: Newest fossil further proof against linear ape progression

Just discovered this year, the fossil find from Ethiopia is just the latest in a series of finds that early humans did not evolve linearly from apes. The latest twist shows what evolutionists consider an ancient human ancestor living in the trees a million years longer than it was supposed to. This despite the fact that Ardi showed humans were walking upright by their dating methods long before.

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"A fossil discovered in Ethiopia suggests that humans' prehistoric relatives may have lived in the trees for a million years longer than was previously thought... The finding will force a rethink regarding the course of early hominin evolution, Harcourt-Smith adds. The addition of a mystery hominin species at this crucial time period suggests that the new species' lineage split from that leading to Lucy earlier in hominin history, and provides further evidence against the idea that modern humans evolved via a linear progression of species from apes."

The fossil also reveals that yet another species lived contemporarily side by side with Afarensis, aka Lucy, and that the grasping big toe of the earlier Ardi, a key feature of bipedalism, continued to still exist at the time:

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"A newly discovered partial hominin foot skeleton from eastern Africa indicates the presence of more than one hominin locomotor adaptation at the beginning of the Late Pliocene epoch. Here we show that new pedal elements, dated to about 3.4 million years ago, belong to a species that does not match the contemporaneous Australopithecus afarensis in its morphology and inferred locomotor adaptations, but instead are more similar to the earlier Ardipithecus ramidus in possessing an opposable great toe. This not only indicates the presence of more than one hominin species at the beginning of the Late Pliocene of eastern Africa, but also indicates the persistence of a species with Ar. ramidus-like locomotor adaptation into the Late Pliocene."